We can know the Pak-Iran relations better if we go back to Indo-Iranian ancestry, but it is better to count the relationship after the establishment of Pakistan in 1947. The relation between two countries started when Iran became the first country in the whole world to know Pakistan.
Iran is considered as the most important neighbor of Pakistan because of its great help. And it is said that in the future these two countries will depend on each other for economic development. The relations between Iran and Pakistan are old and are known all over the world. In fact, some of the cultural things of Iran are adopted by Pakistan.
Well! In Pak-Iran relations, it must be said that the element that binds these two countries together is Islam. If we look at the time before the independence of Pakistan, Pakistani people were closer to Iranians than Indians living in the sub-continent. Pak-Iran relationships were that strong in the late 19th century that Persian was included in the languages spoken all over Pakistan. Even today many of the words of Urdu are taken from Persian language and Persian is taught now in many educational institutes of Pakistan.
Due to some conflicts with Arab countries, Iran became unsecured, but after the emergence of a Non-Arab Muslim country its security became strong. Iran supported Pakistan in every problem after its emergence as a country on the map of the world. First prime minister of Pakistan visited Iran first in 1949 and the head of Iran did the same in the year 1950. In the honor of head of Iran Pakistani national anthem was also played in the year 1950. After this, the relationship between Iran and Pakistan became stronger than ever before. In this way a sense of brotherhood was created according to the Islamic rules and regulations that all the Muslims are brothers to each other.
After the stability of Pakistan, Iran and Turkey along with Pakistan created an organization for social development of the countries that were the part of organization. It was named as Regional cooperation for development (RCD). It was established in 1964. Due to some issues its name was later changed and the organization was called as Economic Cooperation Organization (ECO). This organization bounded all the Muslim countries together. Pakistan was the first country which introduced Revolutionary government in Iran.
Pakistan played a great role in the Pak-Iran relationship. When the war between Iran and Iraq was set, Pakistan tried to settle disputes between the two Muslim countries. The relationship between Pakistan and Iran is really powerful and these two countries share each sorrow and happiness with each other. These two countries considered the Islamic values and acted as brothers to each other.